dittle fsg 71M squelch issue

Hi all, am having an issue with my new to me dittle radio. worked fine for two flights now on startup it breaks squelch for a while even with the switch set correctly. it lasted about 15 minutes then went normal. The next flight it only did that for 5 minutes. after reading the manual it says nothing about being able to adjust auto sq setting. Is there a way to increase the auto squelch? or could the internal battery be getting low? I did the usual turning of stuff to rule out interference from other equipment.